system_wrappers: rename interface -> include

BUG=webrtc:5095
R=tommi@webrtc.org

Review URL: https://codereview.webrtc.org/1413333002 .

Cr-Commit-Position: refs/heads/master@{#10438}
diff --git a/webrtc/system_wrappers/source/file_impl.h b/webrtc/system_wrappers/source/file_impl.h
index e6679aa..06ba582 100644
--- a/webrtc/system_wrappers/source/file_impl.h
+++ b/webrtc/system_wrappers/source/file_impl.h
@@ -14,7 +14,7 @@
 #include <stdio.h>
 
 #include "webrtc/base/scoped_ptr.h"
-#include "webrtc/system_wrappers/interface/file_wrapper.h"
+#include "webrtc/system_wrappers/include/file_wrapper.h"
 
 namespace webrtc {